cosmology

PBS Space Time explains the Hubble constant tension, in which two precise, independent methods of measuring the universe's expansion rate disagree. It covers why this calls some standard cosmology into question.

Astrophysicist Dr. Becky explains the Hubble tension, the disagreement between expansion-rate measurements from the cosmic microwave background and the distance ladder, and what early JWST Cepheid observations add.

PBS Space Time explains Roger Penrose's conformal cyclic cosmology, in which the far future of our universe becomes the big bang of the next. It explores what could come after the universe ends.

Physicist Roger Penrose and philosopher William Lane Craig discuss the origin of the universe on the Unbelievable? show. Topics include Penrose's three realms of reality, conformal cyclic cosmology and whether fine tuning points to a creator.

A PBS Space Time episode asking whether our universe could sit inside a black hole. It covers what physicists think happens inside black holes and the arguments for and against this idea.

Kurzgesagt explores the idea that black holes could create universes and that we might live inside one. It builds up the physics of how density falls as black holes get larger.

Leonard Susskind's Santa Fe Institute talk on the arrow of time: why the past differs from the future when physics equations are time-symmetric. He covers entropy, cosmology and Boltzmann brains.

Kurzgesagt explains why, even with science-fiction technology, most of the universe is permanently out of reach because of cosmic expansion and finite resources.

A PBS Space Time episode asking whether time began at the Big Bang. It explains that the Big Bang is not what most people were taught and what 'start' of the universe really means.

A 29-minute cinematic timelapse by melodysheep that journeys trillions of years into the future, covering the death of the sun, the end of stars, proton decay, black hole evaporation and the fate of the cosmos.

Lawrence Krauss's 2009 talk on the current picture of the universe, how it will end and how it could have come from nothing. It covers the expanding universe, cosmic background radiation and the cosmological constant.

Physicist Angela Collier argues that dark matter is not a theory but a set of observations, covering rotation curves, the CMB and why modified gravity struggles to explain them.

Sabine Hossenfelder explains how her opinion on dark matter has shifted, weighing the evidence for and against it and the case for modified gravity. It runs through what dark matter is and why it has not been detected.

Sixty Symbols interviews Nottingham cosmologist Tony Padilla, who says string theory deserves to be taken seriously. He explains how strings emerged from the equations rather than being invented.

A PBS Space Time episode on how gravitational wave observations of a neutron star merger, GW170817, can limit the number of spacetime dimensions. It is based on a 2018 paper.

A short Nature video on the discovery that our home supercluster is Laniakea, redefined by mapping the flow of galaxies rather than their density. It names the structure with a Hawaiian word meaning 'immeasurable heaven'.

PBS Space Time asks whether dark matter could be made of primordial black holes. It walks through the observational constraints that limit this idea.

Explains the proposed NASA JPL plan to use the Sun as a gravitational lens, sending solar sail craft to its focal region to image an exoplanet's surface. It covers the distances involved, how imaging with the Sun would work and the mission design.

The Eames Office's 1977 film Powers of Ten starts at a picnic in Chicago and zooms out by a factor of ten every ten seconds to the edge of the universe. It then zooms inward to a proton in a carbon atom.

ScienceClic explains why the rubber sheet analogy for general relativity is misleading and offers a new visualization that includes the curvature of time and shows gravity as motion through curved spacetime.

Carl Sagan's narration of the Pale Blue Dot passage, reflecting on the Voyager photograph of Earth as a tiny speck in space. It is a short meditation on humanity's smallness and shared home.

PBS Space Time explains the proposal to use the Sun's gravity as a giant lens, sending a train of small light-sail spacecraft to the focal point roughly 550 AU out. It covers how such a telescope could image exoplanets in surprising detail and the engineering challenges involved.

A visual scale comparison of stars and cosmic objects, from planets up to some of the largest known stars, set to music. It is meant to convey the vastness of the universe.

Veritasium explains, with expert input, that in general relativity gravity is not a force and objects follow straight paths through curved spacetime, including why standing on the ground means you are accelerating.

Cody's Lab builds a 200-billionth-scale model to show how far away the nearest stars are, using parallax and light speed. A short astronomy explainer on interstellar distances.

Stanford physicist Leonard Susskind gives a public lecture on the holographic principle, the indestructibility of information and the nature of black holes. It asks whether the world could be a hologram.

An Isaac Arthur episode on civilizations in the far future, past the Black Hole Era. It covers iron stars, Boltzmann brains, reversible computing and the idea of reversing entropy.

David Kipping presents his proposed Terrascope, a telescope that uses Earth's atmosphere as a lens to achieve enormous magnification. He covers the history of telescopes and his path to the idea, plus Sol-scope and Jupiter-scope variants.

Kurzgesagt's hour-long animated film that compresses Earth's 4.5 billion year history into one hour, roughly a million years per second. It follows the evolution of life through to humanity's tiny final stretch.

Kurzgesagt explains stellar engines such as the Shkadov thruster and Caplan thruster, which could move the Sun and solar system across the galaxy over millions of years to avoid hazards and reach new regions.

A PBS Space Time episode explaining how space and time swap roles inside a black hole's event horizon. It is part of the channel's black hole series.

An Isaac Arthur episode on civilizations in the dark, post-stellar universe, including black hole farming, accretion disks and the Penrose process as energy sources.

Veritasium explains what a black hole should look like, using J.P. Luminet's 1979 work and a cardboard 3D model to show how light bends around it. It was made just as the first black hole image was released.

Leonard Susskind lectures at Stanford on how gravity and quantum information theory have merged into a new way of thinking about physics. He covers entanglement and complexity, with applications from black holes to strange metals and the foundations of quantum mechanics.

Kurzgesagt lays out a speculative plan to terraform Venus, covering its hostile atmosphere and how it might be made Earth-like, with a sources page linked.

A minutephysics explainer showing that the Moon's path around the Sun is not a spiral but closer to a 12-sided polygon with curved corners. It argues the Moon arguably orbits the Sun rather than the Earth.

A Royal Institution event with Sean Carroll and Jennifer Ouellette on what happens if you fall into a black hole, covering the firewall paradox, the information problem and the holographic principle.

A PBS Space Time episode asking whether Venus would be a better colonization target than Mars. It covers Venus's habitable altitudes, floating balloon habitats, and the term surfacism.

A roughly 90-minute film of John Dobson building a Dobsonian telescope step by step, including hand-grinding the mirror.

Isaac Arthur surveys the popular proposed solutions to the Fermi Paradox in a 71-minute compendium. He weighs the strengths and weaknesses of each argument.